The invention relates to fused silica glass. More particularly, the invention relates to fused silica glass having a low absolute refractive index. Even more particularly, the invention relates to a method of providing the fused silica glass with a low absolute refractive index by lowering the fictive temperature of the glass.
Semiconductor optics requires fused silica having, among other things, good homogeneity, low birefringence and resistance to laser damage. Improved birefringence and resistance to laser damage may be achieved by providing fused silica glass having a low absolute refractive index (ARI). Low ARI levels have been achieved for fused silica glasses containing some metal contamination and/or dopants, such as halogens.